The present invention regards the semi-automatic shotgun sector in general and in particular refers to a shotgun with a gas powered system to operate some of its functions.
It is well known that in shotguns having a gas operated system, a part of the gas projecting the cartridge is deviated, through at least one opening, leading from the barrel of the gun to a cylinder/piston unit attached to the barrel. The piston consequently moves in the cylinder due to the pressure of the gas, moving it from a forward rest position to a retracted position, engaging the action of a return spring. By moving into this retracted position, the piston exerts a pressure on a coupling and subsequently on parts which move back towards a tubular ammunition tank so as to carry out, as is well known, different functions such as the ejection of the fired cartridge shell, the re-arming of the firing mechanism and the feeding of a further, new cartridge from the tank to the cartridge chamber in the barrel.
The piston is usually centrally guided, through an interposed seal bushing, on a stationary rod which supports a cover for the tubular tank. The cylinder is closed, on the opposite end from the direction the piston moves when thrust by the gas, by an excess pressure valve placed around a coaxial stem to the guide rod of the piston.
However, in the known solutions the gasses which flow into the cylinder from the barrel and which may contain and/or carry impurities and dirt particles, come into direct contact with the guide rod and the seal bushing between the piston and rod. The result is that as the shotgun is operated, impurities and foreign particles tend to accumulate on the rod and in time hinder the correct functioning of the system, limiting the movement of the piston, causing wear on the bushing and jeopardizing the sealing capacity of the latter.
The present invention is aimed at correcting this inconvenience and disadvantage of the known technique.
It is in fact the aim of the present invention to propose a gas operated system for shotguns equipped with a means to prevent the flow of gas from the barrel to the cylinder coming directly into contact with the piston drive rod so that this rod is less subject to or completely free from deposits of impurities and dirt, and that nonetheless this dirt can easily be expelled from the cylinder.
Another aim of the invention is to propose a gas operated system for shotguns equipped with a means of scraping, which moves together with the piston and is able to remove the impurities from the guide rod of the piston so as to ensure optimum movement at all times of the latter and not jeopardize the action of the seal bushing.
A further aim of the invention is to achieve a gas operated system for shotguns of the type mentioned above in which there is at the same time a way of preventing the gas from coming into direct contact with the guide rod of the piston and a means of scraping in order to keep this rod clean, preventing any dirt particles from depositing.
These aims are reached in a shotgun with a gas operated system incorporating a protective fixed flap placed in front of the gas entrance from the barrel into the cylinder and partially covering the guide rod of the piston, and a scraper blade positioned and operating around the surfaces of the guide rod and which moves together with the piston along the rod itself.